According to an imaging lens used in a vehicle mounted camera, it is requested that a focusing aberration characteristic of a total of an effective screen is excellent although the lens is of a wide angle in order to ensure an excellent field of view over a wide range and small-sized and light-weighted since a space of mounting the camera in the vehicle is limited.
In a background art, there is known such a wide angle imaging lens described in, for example, JP-A-2003-307674 and JP-A-2003-232998.
In recent years, particularly in- a wide angle imaging lens mounted to a vehicle mounted camera, it is requested to achieve further small-sized formation, light-weighted formation while maintaining an excellent optical function.
However, according to the wide angle imaging lens described in JP-A-2003-307674 and JP-A-2003-232998, although brightness can be ensured, since the lens is mainly constituted by glass spherical lenses and a number of lenses is as large as 5 through 6, there poses a problem that it is difficult to meet the request in view of a size and a weight thereof.
Further, although there is also known a wide angle imaging lens achieving small-sized formation, light-weighted formation by reducing a number of constituent lenses by using aspherical lenses, heretofore, according to a constitution using the aspherical lenses, it is indicated that an optical function is not sufficient and particularly, lateral color is not corrected sufficiently and there is a concern of bringing about spread of color (refer to JP-A-2003-232998).
A fish eye wide angle lens including four lens elements is disclosed in JP-A-2005-227426 published on Aug. 25, 2005.